Checkpoint: Human Digestion
Sherrie H. Lu
The digestive process starts with saliva. Saliva begins with the scent or sight of food. Food enters the digestive system starting at the mouth. Food is broken into smaller pieces by your teeth. The broken up pieces of food mix with saliva and break down into a substance called bolus, which is a ball of chewed food. Bolus then passes through the pharynx, which helps us swallow, into the esophagus and into the stomach. The stomach further breaks down the bolus with highly acidic stomach secretion and is turned into a semi liquid mass called chyme. This process could take 2 to 6 hours depending on the amount of food and type of food. The chyme then moves to the small intestine. The small intestine is 20 feet long and takes 3 to 5 hours for chyme to move through the small intestine. This is where most of the nutrients are absorbed. While moving through the small intestine additional secretions are produced from the liver, gallbladder and pancreas to assist in the digestive process. The chyme that is not absorbed is then deposited into the large intestine through a sphincter. The sphincter prevents any substances from reentering the small intestine. The large intestine is 5 feet long and the break down process can take 24 hours. The large intestine is the last chance to absorb any leftover nutrients. As chyme travels through the colon some left over water, vitamins and minerals are absorbed. Any substances left are moved to the rectum and stored until it moves to the anus for elimination.
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